Multi-modal imageability and degradation characteristics of high-borate glass systems for transient embolization

• Published in: Journal of non-crystalline solids 2019-04, Vol.510, p.26-35
• Main Authors: Doucet, J., Tonkopi, E., Nuschke, A., Tremblay, M.L., Brewer, K., Beyea, S., Filiaggi, M., Abraham, R., Werner-Zwanziger, U., Boyd, D.
• Format: Article
• Language: English
• Subjects: Bioactive glass; Boron glass; Degradation; Mixed cation; Radiopacity; Transarterial embolization
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2019.01.014

Two glass series were developed based on the substitution of a monovalent glass modifier for a di- or trivalent ion in a high borate glass system. The BRS series consists of compositions 0.70 B2O3–0.30-X Rb2O – X SrO, and the BRG series consists of compositions 0.70 B2O3–0.30-X Rb2O – X Ga2O3, where 0.00 ≤ X ≤ 0.10 in increments of 0.2. All glasses were characterized in order to examine their composition-structure-property relationships, and to assess their potential for use as degradable, radiopaque embolic agents. Glasses were melt quenched, and evaluated in terms of structural changes (11B MAS-NMR, density, and glass transition temperature), changes in radiopacity (both CT and MRI), and changes in degradation timeframes under simulated physiological conditions. Structural analysis determined there was no change in the B4% of the BRS series, despite a linear increase in density and Tg. The strontium acts as a crosslinker, creating a more hydrolytically stable network, which leads to longer dissolution times. Conversely, the BRG series displayed a linear decrease in the B4%, a decrease in density (Tg data not available), yet a slight increase in hydrolytic stability is also observed. Gallium most likely acts more as a glass former than a glass modifier, thereby sequestering oxygens from the tetrahedral boron centers, creating trigonal B3 centers and tetrahedral gallium. All glasses were found to be imageable on CT (intensity > 3200 HU at 120 kVp), and invisible on clinical MR imaging modalities. •Borate glasses offer good degradation and imageability properties for embolization•Changing the composition of the glass system drastically alters its properties•Substituting rubidium for strontium significantly decreases hydrolytic degradation•All glass series studied demonstrated good contrast on computed tomography imaging•The strontium series studied shows promise as a new transarterial embolic agent